Wintermobile

I have what I think is an interesting idea for a cold weather car. Cars generally drive through environments colder than their engine, even in the desert, though this will gain the most usefulness in the more freezinger parts of the world. The car would have pipes going all throughout its outer chassis. The pipes would be full of an antifreeze and water mixture, and would end on either side in a bypass valve.
In cold weather, the driver can flip a switch, to open the valve, and now circulate the coolant in the car around the entire body of the car. Much heat leeches out the top, into the driving compartment, and out the back. In cold weather, it'd feel nice.
The engine would also benefit. Gasoline engines work by heat exchange -- the more heat it can pump out, the more efficiently the engine works. Coolant would come in cold as can be, and the solid parts of the car would have fewer heat differences over time. With fewer heat differences, there's less thermal stress.
I think taking this car to a hot region, though, like a jungle or a desert, would be worse than a conventional car.